This is one that I thought was compelling.[1] The trial ultimately failed but if you read the results the post-hoc analysis, it showed promise in mild and moderate subgroups of the ITT population. Most drugs today don't even target mild AD, but go after pre-symptomatic patients.
There was also benefit across most measures, but just not of statistical significance.
The trial had some major problems with appropriate controls, and is widely cited as a poster child for why the FDA should not require a control group to undergo invasive brain-surgery, and how this can taint the results.
It also showed a 89% reduction in amyloid Beta, the same proxy measure Biogen's aducanumab was recently approved based on.